1988 125hp Force lower unit woes

[Sandy-man]

The washer that sits on the inside face of the forward gear determines the end float play and is called a thrust washer. A collar on the propeller shaft pushes up against this thrust washer. Some may call it a "shim", but they are the same thing.

In the service manual it suggests an end float play between .005" - .020". In the manual it states to remove the shift yoke before measuring for end float. So the shift rod is not engaged with the prop shaft at all. But in order to do this you will have to remove the gear box cover for access to the shift yoke. Which isnt difficult but can be a pain to deal with as the shift yoke can easily fall off the end of the shaft when installing. Having it in gear may give you inaccurate end float measurements but dont quote me on that. I am just relaying the info in the manual.

Since the book calls for between .005" - .020" I think you may have to address it. Seems like .110" is excessive. Make sure the thrust washer is still on the forward gear and is not severely worn or the face of the forward gear it rides on is not worn.

The only "shim" BEHIND the forward gear is going to be behind the race for the forward gear roller bearing. Some have a shim there and some do not. Since you are not replacing the forward gear and its race I would not worry about this.

Double check that forward gear thrust washer and make sure its not damaged or missing. With that much play i bet the washer isnt even on there. You can find them on marineenginecom and look up your engine model number. They have varying thicknesses you can order. DO NOT put any ordinary washer in there. You will damage the gearbox in doing so. These shims ares specifically designed for this application.

The factory .059" thrust washer is on there, my dial calipers says it's only .057" but close enough. No apparent wear to the face of the forward gear where this washer resides or to the washer itself. What I find really weird, or at least I don't understand, is when I put the propeller back on there doesn't seem to be any shaft end float at all.

 

[Jiggz]

Well, not really sure how you were able to turn the top stop nut down without turning the lower stop nut. Both of these nuts should be tight holding on the shift lever linkage from the control cable. It could be that this is the source of your problem that the top stop nut has loosened thus not pulling the shift rod high enough to engage the reverse gear accordingly. Hopefully, this resolves your problem. Let us know.

 

[DunbarLtd]

The factory .059" thrust washer is on there, my dial calipers says it's only .057" but close enough. No apparent wear to the face of the forward gear where this washer resides or to the washer itself. What I find really weird, or at least I don't understand, is when I put the propeller back on there doesn't seem to be any shaft end float at all.

Theres a tapered section on the prop shaft that the thrust washer (prop thrust washer this time) will butt up against and cant go any farther. The prop hub is tightened flush against this washer.

This taper will not allow the hub or the prop housing to contact the gear housing. Check and make sure this is not the case.

Because of the thrust washer stopping at the taper on the shaft the prop nut when tightened will not put any pressure on any components in the gear case. So end float should not change just because the prop is on.

Maybe remove prop and make sure it isnt touching the gear case and check end play again. But Id like to remind you in the manual it says to remove the shift rod from the prop shaft before measuring end play.

Hopefully the shift rod adjustment will keep it in gear and solve the problem but id be concerned if there is excess end play. I dont have enough experience to know what kind of damage it will cause but I cant see it doing any good.

Im curious to know the outcome so please come back and update.

Good luck!

 

[jerryjerry05]

To access the double nuts: remove the plenum in front of the rod.
4 tiny screws 1/4 or 5/16 socket.

 

[Sandy-man]

To access the double nuts: remove the plenum in front of the rod.
4 tiny screws 1/4 or 5/16 socket.

Yes, 5/16, this I had to do and even then it was tight and very difficult to see what I was doing.

 

[Sandy-man]

Well, not really sure how you were able to turn the top stop nut down without turning the lower stop nut. Both of these nuts should be tight holding on the shift lever linkage from the control cable. It could be that this is the source of your problem that the top stop nut has loosened thus not pulling the shift rod high enough to engage the reverse gear accordingly. Hopefully, this resolves your problem. Let us know.

I did turn the bottom but down 1 full turn first, then tightened the top nut down onto the linkage. Heading for the lake here in about an hour or so.

 

[Sandy-man]

Well I never made it to the lake. Instead I thought it would be smart to start the motor at home first with the muffs on. This would be the first time starting it since it overheated and shut down in the middle of Lake Erie. It wouldn't start, got several Puffs and 2 back fires. After the 2nd backfire it would only turn over, no sign of wanting to start. Could be the battery getting a touch too low, enough to turn it over good but not enough for ignition? On the bright side, it shifts in and out of forward and reverse seemingly OK. Of course can't know for sure without running it. So now I guess I have to run a bunch of other tests, is it still getting spark, compression, probably rebuild the carb (diaphragm shot?), also going to clean out the cylinder drains and check Reed's, replace all gaskets and screens. Should I pull the flywheel and check the key to make sure it's in the keyway correctly? Getting to be a bit more than I wanted to tackle but if I ever want to get my boat back on the water I either do this or replace the motor. Are these Force motors worth my time and effort or are they truly junk like my retired boat mechanic said they are?

 

[Jiggz]

The engine overheated. Normally, the first thing to check is compression. If all is good then check the basics, spark, fuel and then timing. Usually, unless the flywheel key is sheared the timing will not move unless you actually disconnected the towershaft or dismounted the trigger. To check flywheel key, just check #1 cylinder TDC with flywheel marking. If still aligned then you can assume timing is OK.

With fuel, you should already have a clear fuel filter between the fuel pump and the carbs inlet. It should be full and same with the bowls.

As for the starter, this is crucial in the sense that it might be rotating but not fast enough due to low battery or due to an old starter that needs to be cleaned. Try jumpering it with a known good battery and it still would not start, post a video so we can assess if it's actually rotating fast enough or need to refurbish the starter.

Godluck.

 

[Sandy-man]

I don't know what just happened but my dumb smart phone just popped up a message that said "Report has been sent". As though I reported a post or something. ??? I apologize now for anything that may become of that because I have nothing to report.

 

[achris]

I don't know what just happened but my dumb smart phone just popped up a message that said "Report has been sent". As though I reported a post or something. ??? I apologize now for anything that may become of that because I have nothing to report.

All good.

Chris......
iboats mod team.

BTW, forums aren't designed to be accessed by phones facepalm, and so results can be 'unpredictable'. Best stick to a computer keyboard in future.

 

[Sandy-man]

All good.

Chris......
iboats mod team.

BTW, forums aren't designed to be accessed by phones facepalm, and so results can be 'unpredictable'. Best stick to a computer keyboard in future.

Unfortunately, I don't own a computer so I am stuck toughing it out with the unpredictable. Cool website though, lot of nice people on here. Thanks for the response!

 

[jerryjerry05]

You said(It wouldn't start, got several Puffs and 2 back fires. After the 2nd backfire it would only turn over, no sign of wanting to start.)
Any time it backfires, could be a flooded situation?
The results of a backfire, even a small one: the port cover gaskets can be blown out and then start sucking air??

Like Jiggz suggested, check thecompression, timing and flywheel key.
You can have spark and fuel but if the key's sheared, it' won't ever do anything but backfire.
One cyl. with low comp. can cause the hard turning over.




You asked?(Are these Force motors worth my time and effort or are they truly junk like my retired boat mechanic said they are?)
I had 4 1988 85 hp. on 2 different 21ft.boats, I put thousands of hrs. on these motors. Used them from Deleware Bay to
the Chesapeake and off shore in the Atlantic in Virginia and down in Fl.
I wouldn't hesitate to use them to go anywhere.
It makes no difference the brand. If your 3K Force is gonna break down it will,
So will your 20K Yamaha.
The parts are readily avaiable for just about all the Chrysler and Force motors.​

 

[Sandy-man]

You said(It wouldn't start, got several Puffs and 2 back fires. After the 2nd backfire it would only turn over, no sign of wanting to start.)
Any time it backfires, could be a flooded situation?
The results of a backfire, even a small one: the port cover gaskets can be blown out and then start sucking air??

Like Jiggz suggested, check thecompression, timing and flywheel key.
You can have spark and fuel but if the key's sheared, it' won't ever do anything but backfire.
One cyl. with low comp. can cause the hard turning over.




You asked?(Are these Force motors worth my time and effort or are they truly junk like my retired boat mechanic said they are?)
I had 4 1988 85 hp. on 2 different 21ft.boats, I put thousands of hrs. on these motors. Used them from Deleware Bay to
the Chesapeake and off shore in the Atlantic in Virginia and down in Fl.
I wouldn't hesitate to use them to go anywhere.
It makes no difference the brand. If your 3K Force is gonna break down it will,
So will your 20K Yamaha.
The parts are readily avaiable for just about all the Chrysler and Force motors.​

I guess I don't know what the port is where the cover gaskets could be blown out. Is the same as the cylinder drains? Are these the ports?

 

[Sandy-man]

Here's a pic of what I think you're talking about?

 

[Sandy-man]

I believe this is TDC, and number one piston is at TDC.

 

[Jiggz]

Yup, that's TDC indicating the flywheel key is not sheared. Double check the plug wires make sure they've not been switched around. While at it, check the fuel at the carb's bowl. If there is fuel and you have sparks (use an inline spark tester) and compression is good on all cylinders, try starting it again. But this time have a spray bottle with fuel-oil mix in it ready at hand. And also remove the two air covers at the front of the carbs.

Before starting, with a flashlight check the position of the throttle butterflies way behind the throat of the each carb (Do not confuse it the choke butterflies at the front). There should be a slight opening in starting position. If not, place the throttle control in high rpm idle position and watch if the throttle will open a bit. You cannot start or make an engine fire with throttle fully closed.

Have a second person do the starting. Engage the choke and make sure the choke butterflies activate (closed to about 3/4 position) and crank it over. If it puffs but not fires, then try again this time without choking.

If it doesn't start or even puff for the first time cranking of about 5-8 secs. Then try again without choking while at the same time spraying fuel oil mix into each carb. If it fires or puffs with spraying, it tells you have fuel delivery or carbs problem or the more unlikely reed problem.

 

[jerryjerry05]

#51-52 is the cover and the gasket's not in the pic.
Hard to tell if the gaskets letting air in.
Do the starting fluid test.
If it coughs or stutters, stalls even running better can show a bad gasket.

The dogbone #35 is part(cover) of the recirc. system.


Reeds: any blowback from the front of the carbs?

If there's a cough or backfire at startup, that might be a flooded motor,
if it continues after starting then it might be sucking air.
Do the starting fluid test.

 

[Sandy-man]

#51-52 is the cover and the gasket's not in the pic.
Hard to tell if the gaskets letting air in.
Do the starting fluid test.
If it coughs or stutters, stalls even running better can show a bad gasket.

The dogbone #35 is part(cover) of the recirc. system.


Reeds: any blowback from the front of the carbs?

If there's a cough or backfire at startup, that might be a flooded motor,
if it continues after starting then it might be sucking air.
Do the starting fluid test.

So 50 in this diagram is the gasket you're talking about. Thank you for the clarification.

 

[jerryjerry05]

Yup that's the one.
The OEM, the edges were fairly thin and they were just installed with no sealer.
If you remove? They should be replaced and silicone sealer used.
Let the silicone cure and tuorqed down.

 

[Sandy-man]

Yup that's the one.
The OEM, the edges were fairly thin and they were just installed with no sealer.
If you remove? They should be replaced and silicone sealer used.
Let the silicone cure and tuorqed down.

Thanks, Jerry, I will do the starting fluid test first. If it shows there is a leak I will replace the gasket and use silicone with it.